1. Field of Invention
The present invention relates to automated transfer or programming of operating codes and data into programmable electronic devices.
2. Description of Prior Art
In the semiconductor industry, a considerable number of electronic devices are provided by vendors in programmable form with blank memories or unspecified connections between arrays of logic circuits. Users can then custom configure or program the electronic devices to perform their intended functions by programming them, transferring or "burning in" a sequence of operating codes into the memory, or by specifying a particular arrangement of gating logic connections.
Special purpose programming machines, known as device programmers, have been developed to allow designers and engineers to rapidly transfer these codes, gating logic arrangements and the like into the programmable devices. The initial type of device programmer was a stand alone or single device programmer, allowing an operator to insert and program individual devices according to end user requirements. The programming pattern for the device was transferred into the device from a device programming computer or logic circuit.
The more recent type of device programmers developed were known as gang programmers. These were intended for large production runs of the same type or model of programmable device. An array of device programming sites like the single site station ones operated in parallel in a common programming sequence according to production programming odes from a single central computer. A set or production run group of devices would be loaded into the array of programming sites. When the sites were loaded, the array of devices was then programmed in a common, ganged sequence, each device starting and completing the programming sequence in common with each of the other devices.
There were, however, several undesirable features to gang programming. One of these was time inefficiency. When the programming machine was being loaded with blank devices by the operator, none of the programming sites was operating due to the required common starting and operating sequence. Further, once the programming machine was loaded and started into the programming run, the machine operator was idle until the gang programming sequence was completed.
Also, it was difficult to monitor the status or progress of the programming. If a machine operator was distracted or interrupted when loading or unloading an array of programming sites, it was very difficult without repeating the programming cycle to determine whether the devices were either beginning blank ones or completed programmed devices because the gang programmer or conventional programmer's status indicator continues to indicate that the last device programmed in each site was successfully programmed even after the successfully programmed device was removed and a blank device was inserted into the programming site. Additionally, a number of types of semiconductor devices, due to increasing productivity requirements, might have slightly, but not inconsequentially, different operating parameters or characteristics. An example would be the programming voltage level. These variations might even occur among devices in the same production run from the semiconductor manufacturer. Nevertheless, gang programming might be attempted of a number of such devices based on an assumed existence of common parameters. If there were in fact variations in the operating parameters, even if minor ones, gang programming could result in flawed or defective production of programmed devices because the gang programmer applies similar waveform voltages and pulse widths to each of the devices being programmed in the set.
One disadvantage of gang programmers was software complexity. The software had to be written such that it can apply waveforms to all devices simultaneously and verify that each programmed device verifies correctly. As programming algorithms increased in complexity to handle more complex devices, the difficulty in writing such software increased disproportionately.
The only available option for many users was to operate a number of conventional single-site programmers side by side. Doing so allowed increased operator efficiency, but also some disadvantages. First, each site was a separate and complete programmer, thus duplicating the user interface and the algorithm storage requirements, thereby increasing cost and complexity. Second, each system was configured by the user independently, thus taking time and allowing simple operator error to cause quality problems. Third, each system's status was reported separately, so status of the total operation was indeterminable except by manual methods. Finally, if a new algorithm was required to program a particular type of device, each station was required to be loaded with the new algorithm.